vcl中的TApplication.CreateForm源码解析
请问大家下面这段代码的含义。我以前学c++，对类引用不太熟。请大家指教。

procedure TApplication.CreateForm(InstanceClass: TComponentClass; var Reference);
var
  Instance: TComponent;
begin
  Instance := TComponent(InstanceClass.NewInstance);
  TComponent(Reference) := Instance;
  try
    Instance.Create(Self);
  except
    TComponent(Reference) := nil;
    raise;
  end;
  if (FMainForm = nil) and (Instance is TForm) then
  begin
    TForm(Instance).HandleNeeded;
    FMainForm := TForm(Instance);
  end;
end;

[解决办法]
哪下行看不懂，神奇在这里Instance.Create(Self);